Apparatus for color photography.



R. BERTHON.

APPARATUS FOR COLOR PHOTOGRAPHY.

APPLICATION FILED 191-13.4, 1909.

Patented May 16, 1911.

Wiinesses UNITED STATES PATENT oFnIoE.

RODOLPHE IBERJDHON, OF LYON, FRANCE.

APPARATUS FOR COLOR PHOTOGRAPHYQ Specification of Letters Patent.

Patented May 16,1911.

Application filed February 4, 1909. Serla1 No. 476,161.

lines or dots.

It is well known that ifa diaphragm with three apertures respectively covered by suit-. ably selected red, green and blue violet screens is placed in the optical center of an objective, the colors of the images projected are not modified, but remain identical with the colors projected by the same objective without the tri-chromatic diaphragm. Moreover, examination of the projector from the plane of the projected image shows that the brilliance of the screens of the diaphragm varies according to the color of the particular part of image View, and according to the components of the color in question. Thus in the case of a yellow portion of the image, only the red and green screens will appear illuminated, and the violet screen will appear black. It follows from this that if at each point of a single sensitized layer a complete, infinitely small image of the objective with itsthree screens can be recorded, a 'tri-chromatic selection will be efiected analogous to that obtained by the processes in which juxtaposed colored pigments are used, and if the image is projected by means of the apparatus whichhas served for producing the impression the exact colors of the original are reproduced. This can be efi'ected by various means, which will be described hereinafter with reference to the accompanying drawings.

Figure 1 is a section of an anastigmatic objective with tri-chromatic screen, and Fig. 2 is' a longitudinal section of a camera equipped with devices embodying my invention. Fig. 3 is a front view of the screen. Fig. 4 is a front view, on a considerably enlarged scale, of a plate or film with hemi-, spherical, transparent; refractive protuberances, and Fig. 5 is a section on the line 5-5 of Figs. 4 and 6. Fig. 6 is a front view,

on enlarged scale, of a plate or film with parallel, transparent, refractive rid es, and. Fig. 71s a front view of another orm of screen.

For the purposes of the invention an objective is used which has in its optical cen-' ter a diaphragm consisting of red, green and blue screens, marked in the drawing (Figs. 1 and 7) A, B and C respectively, or A B C (Fig. 3). There is also used a suitable refractive surface for example one covered with minute spherical protuberances D of microscopical proportions (Figs. 4 and 5), so that each pointthereof acts as a true objective. The same result can be obtained by substituting for this protuberant surface colorless, refractive, spheroidal grains,.which serve the same purpose as the facets of the aforesaid surface. If the screens of the diaphragmare apportioned into a series of microscopical parallel transparent portions,

as hereinafter described for example in reference to Fig. 3 linear images of the objective may be used instead of complete micrographic images. Instead of the protuberant surfaces hereinbefore referred to, surfaces With semi-cylindrical ridges E (Figs. 5 and 6) are in this case preferably used, or colorless, cylindrical filaments, consisting of single strands, are placed on the surface.

To prevent halation when the projection is being efi'ected it is advisable to have the sensitive layer F and the ray-selecting surface D or E carried by the same support G, which may be of glass, celluloid, gelatin or other material. Plates or films may thus be prepared for ordinary views or for kinematographic purposes, etc.

' The images obtained by the process described may be used in rojection in various ways. If simply devel c iped after exposure through the objective with tri-chromatic diaphragm, the plate or film, returned to the apparatus by means of which the view was taken, gives a negative image in, which the colors of the objects are represented by their complementary colors. If the development is reversed (or positive) the projected lmage is positive and shows the real colors. Finally, the negatively developed image or the positively developed image may be projected by means of the original objective but with diaphragm screens of complementary colors. In the first case the projection is negative, but the colors are similar to those of the object; in the second case the projecorder that the surface of the image may beare used tion is positive, but the colors are complementary to those of the object.

The tri-chromatic screens in the objective may be modified so as to produce on the sensitive layer a reticulated image capable of being projected without colored screens in the projecting objective. For this purpose the screens of the tri-chromatic diaphragm are striated with opaque lines, as shown in Fig. 3, the number of striae being inversely proportional to the lengths of the fundamental waves of each colored screen; thus the striae in the blue violet screen C are closer together than those in the green screen B, and the striae in the reen screen are closer together than those in thered screen A. In practice the number of striae must be such that their linear projection on the sensitive layer gives at least sixteen lines per millimeter in the case of the red, nineteen in the case of the yellow-green, and twentytwo in the case of the blue-violet.

If the plates or films previously described or ex tri-chromatic lms register in all the zones corresponding to the radiations of the respective colors. It must be noted that in integrally reticulated the distance of the ridges or protuberances from the sensitive layer must be lncreased so that the linear projectlons of the three screens become mingled. The result is the same as if, during the exposure, three screens of the primary colors, lined in accordance with the lengths of the fundamental waves, were successively brought into contact with the sensitive layer; at the differently colored points of the image the different networks of lines register.

osure the opaque lines on the' This would not, however, allow of *simultaneousl registering the diflerent colors, as does t 'e striated tri-chromatic diaphragm shown in Fig. 3.

Exposed to light at a suitable angle, an image produced in -the manner described presents the true colors of the object, by reason of simple refraction.

\Vhat I claim as my invention and desire to secure by Letters Patent of the United States is 1. An apparatus 'for producing projecb.

able and reproducible proofs in colors, comprising an objective, a diaphragm in the objective having atri-chromatic screen, a sensitive surface, and means interposed between the sensitive surface and the objective, whereby the images of the screen are separated by refraction at points close together, and projected in a microscopic state on the sensitive surface.

2. An apparatus for producing projectable and reproducible proofs in colors, comprising an objective, a diaphragm in the objective having a tri-chromatic screen, said screen striated with lines in numbers inversely proportional to the fundamental wave lengths of the colors of the screen a sensitive surface, and means inter osed etween the sensitive surface and t e objective, whereby the images of the screen are separated by refraction, and projected in a microscopic state on the sensitive surface.

In witness whereof I have signed this specification in the presence of two witnesses.

RODOLBHE BERTHON.

Witnesses:

JEAN GERMAIN, GUILLAUME P1001112. 

